Smoothing or finishing trowel



y July 11195 S--fCI-'iPSON- `-'.2`;,51'4,626

v sMooTx-'IING RIFINISHING TRowEx.

Filed sept. 22, 1947 1 Inventor By.V

Patented July 11, 1950 2,514,626 SMOOTHING OR FINISHING TROWEL SamuelClipson, London, England Application September 22, 1947, Serial No.775,556 In Great Britain October 4, 1946 3 Claims.

This invention relates to hand trowels or screeds, particularly for usein finishing or smoothing the surfaces of slurries applied to walls,ceilings and the like.

I h'ave found that with certain so-called wallsurfacing compositions, abetter finish is obtained by subjecting the hand screed when in use to arapid vibratory motion.

Accordingly, the invention provides, as a new article of manufacture, ahand screed incorporating pressure fluid operated means whereby it canbe subjected to transverse vibration while being manipulated over thesurface to be finished or smoothed.

Preferably, the said pressure uid operated means comprises aplunger-type vibrator fixed on the blade of the screed, the plunger ofthe vibrator working in a cylinder suitably ported for the supply ofmotive fluid and for the exhaust of the expanded fluid as required toset up rapid vibration by repeated impact of the plunger against theends of the cylinder.

The screed proper may be of any desired size and cross-sectional shape(fiat, arcuate and so forth).

One form of vibrating hand screed is illustrated on the accompanyingdrawing, on which:

Fig. 1 is a face view of the screed;

Fig. 2 is a corresponding end view; and

Fig. 3 shows the vibrator in longitudinal section on line III-III ofFig. 2.

The screed blade I is secured to a bent metal strap 2 by a bolt 3 andnut 4, and the strap is secured by a bolt 5 and nut 6 to the cylinder 1of a. plunger type vibrator. An elongated handle 8 for holding andmanipulating the screed is secured by bolts 9 and nuts I0 to a yoke I Iwhich is also secured to the vibrator cylinder 1 by means of the bolt 5and nut 6.

As shown in Fig. 3 the barrel of the vibrator cylinder 1 is stepped asalso is the plunger I2` therein. A connection I3 for pressure air opensinto the part of the barrel of larger diameter. Further, this part ofthe barrel has a series of exhaust ports I4, while the part of smallerdiameter has a series oi.' exhaust ports I5. The plunger I2 Ihas anaxial passage I6 open to its larger end and communicating with radialports I'I opening to the periphery oi.' its smaller part.

When pressure iluid is admitted via I3 it first moves the plunger to theleft in Fig. 3, air in the larger part of the barrel then exhausting viaports I4. As the plunger reaches the end of this stroke these ports areclosed and pressure air passes via ports I1 and passage I6 to the largerend of the plunger to return the plunger. During the return stroke airin advance of the plunger is exhausted via ports I5. Thus, the plungeris rapidly reciprocated so long as pressure air is supplied to theconnection I3.

This rapid reciprocation of the plunger I2 vibrates the cylinder 1 andtherefore the screed so that the working surface Ia of blade I issubjected to a tamping action whilst it is manipulated over the surfaceto be smoothed or finished. This movement produces coacting cornponentsof forces that are effective in establishing both an impacting actionand a smoothing action through the trowel blade on the surface beingtreated.

Reference 'is made to my copendng patent application Serial Number775,555, filed September 22, 1947 for Compositions for Surfacing Walls,Ceilings and the Like, for an explanation of the compositions with whichthe smoothing or iinishing trowel of my invention is employed. Referenceis also made to my copending application Serial Number 6,233 ledFebruary 4, 1948 and patented as Patent No. 2,504,805, for Method andApparatus for Applying Slurries to Structural Surfaces, for informationregarding the appli cator and method of employing the same.

I claim:

l. A hand screedl for use in finishing the surface of slurries appliedto structural surfaces comprising in combination a cylinder, a brackethaving an angularly inturned portion attached at one end to saidcylinder, an elongated trowel blade secured to the inturned portion ofsaid bracket, a working surface on said trowel blade, a handle securedto the side of said cylinder opposite said bracket, a reciprocatingpiston in said cylinder, and means for rapidly reciprocating said pistonwhereby rapid Vibratory pulses are transmitted to said trowel blade inthe direction of movement of the piston and with a component normal tothe working surface of the trowel blade.

2. A hand screed as set forth in claim 1 in which said handle is securedto the side of said cylinder through a yoke that extends at an anglewith respect to the axis of said housing.

3. A hand screed as set forth in claim 1 in which said handle isconstituted by a transversely extending bar projecting substantiallyparallel to the axis of said trowel blade.

SAM'UEL CLIPSON.

REFERENCES CITED The following references are of record in the le ofthis patent:

UNITED STATES PATENTS

